A study of C. difficile found that many antibiotic resistance genes are shared between pigs and humans

Study investigates samples of superbugs Clostridioids Difficult across 14 pig farms in Denmark find that sharing Multiple antibiotic resistance genes between pig and human patientsand provide evidence of that It is possible for this animal to be transmitted to humans (zoonotic).

The study, conducted by Dr. Samih Bedjaoui and colleagues from the University of Copenhagen and the Serum Statins Institute in Denmark, is being presented at this year’s European Conference on Clinical Microbiology and Infectious Diseases (ECCMID) in Lisbon, Portugal (23-26 April).

Our discovery of multiple, shared resistance genes indicates that Clostridium difficile is a repository of antimicrobial resistance genes that can be exchanged between animals and humans. This disturbing discovery indicates that antibiotic resistance can spread more widely than previously thought, and confirms links in the chain of resistance that extends from farm animals to humans.”

Dr.. Samih Bedjaoui University of Copenhagen

Clostridium difficile is a bacterium that infects the human gut that is resistant to all but three current antibiotics. Some strains contain genes that allow them to produce toxins that can cause harmful inflammation in the gut, leading to life-threatening diarrhoea, especially in the elderly and hospitalized patients who have been treated with antibiotics.

Clostridium difficile is one of the biggest threats to antibiotic resistance in the United States—and caused an estimated 223,900 infections and 12,800 deaths in 2017, at a health care cost of more than $1 billion. [1].

A hypertrophic strain of Clostridium difficile (ribotype 078; RT078) that can cause more serious disease and its major sequence type 11 (ST11), is associated with an increased number of infections in the community in healthy individuals and young adults. Farm animals were recently identified as RT078 tanks.

In this study, Danish scientists investigated the prevalence of Clostridium difficile strains in cattle (swine) and the potential for the spread of antimicrobial resistance genes by comparison with clinical isolates from Danish hospital patients.

Fecal samples were collected from 514 pigs in two batches from farms across Denmark between 2020 and 2021. Batch A included 330 samples of pigs, pigs and slaughter pigs from fourteen farms in 2020. 184 samples were collected in batch B during slaughter in 2021.

The samples were screened for the presence of Clostridium difficile and genetic sequencing was used to determine if they contained genes that were resistant to toxins and drugs. Genome sequencing was also used to compare Clostridium difficile isolates from pig samples with 934 isolates collected from patients with C. difficile infection during the same period.

Of the 514 pig samples, 54 had evidence of Clostridium difficile (batch A = 44, batch B = 9). Further analyzes of 40 samples (batch A = 33, batch B = 7) found that Clostridium difficile was more common in piglets and piglets than in butchered pigs. The authors speculate that this may be due to the difference in age between young pigs and adult pigs; Younger pigs have a microbiota composition that makes them more susceptible to successful colonization.

In total, thirteen types of sequences found in the animals are identical to those in the patient’s stool samples. Strain ST11, related to the animal, was the most common (pig = 21, human = 270). In sixteen cases, the ST11 strains in humans and animals were identical (see Table 1 and Figure 1 in notes to editors)

All isolates from animals were positive for the toxic genes and ten of them were highly virulent, with a greater ability to cause disease.

In all, 38 animal isolates contained at least one resistance gene; Overall, resistance to seven classes of antibiotics was predicted, the most common being macrolides, beta-lactams, aminoglycosides and vancomycin-; It is important for the treatment of severe bacterial infections.

“The overuse of antibiotics in human medicine and as cheap production tools on farms is undermining our ability to treat bacterial infections,” says Dr. Bedjaoui. “Of particular concern is the large reservoir of genes that confer resistance to aminoglycosides, a class of antibiotics that are intrinsically resistant to Clostridium difficile – they are not essential for resistance in this species. Clostridium difficile thus plays a role in spreading these genes to other susceptible species. to injury”

She continues: “This study provides further evidence of the evolutionary pressure associated with the use of antimicrobials in animal husbandry, which critically selects resistant human pathogens. This highlights the importance of adopting a more comprehensive approach, to the management of Clostridium difficile infection, in order to consider all Possible publishing methods.

Despite the significant findings, the authors note several limitations, including that they were unable to determine the direction of transmission. As Dr. Bedjaoui explains, “The fact that some lineages in both human and animal isolates were identical suggests that they may be shared between groups, but until we perform deeper phylogenetic analyzes we cannot determine the direction of transmission, which can also be bidirectional, as the The exchange and expansion of bacteria is continually in the community and farms.”


European Society of Clinical Microbiology and Infectious Diseases


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